The water tank is put in place on Haiyang 1 (Image: SNPTC)
The 285-tonne containment cooling tank (large round component) is a major part of the AP1000's safety systems. It will hold some 3000 cubic metres of water ready to flow down to evaporate from the surface of the containment vessel in any emergency situation where the reactor system may be overheating. This evaporation would help to cool the overall system. The water could also be directed to top up the used fuel pool, while the tank itself can be refilled from water stored elsewhere on site.
In September 2007, Westinghouse and its partners the Shaw Group received authorization to construct four AP1000 units in China: two at Sanmen in Zhejiang province and two more at Haiyang in Shandong province.
The construction of the Haiyang AP1000s is being managed by Shandong Nuclear Power Company, in collaboration with State Nuclear Power Technology Corp (SNPTC) and China Nuclear Energy Construction Corp. SNPTC has a major role in the transfer of knowledge and technology from the plant supplier, Westinghouse.
Sanmen unit 1 is expected to be the first AP1000 to begin operating. The unit is scheduled to begin generating electricity in 2014. Haiyang 1 is also slated for commercial operation by the end of this year. All four Chinese AP1000s are scheduled to be in operation by 2016. Third and fourth units are planned at both Sanmen and Haiyang.
Four AP1000s are also currently under construction in the USA: Vogtle 3 and its sister unit Vogtle 4 in Georgia, and Summer units 2 and 3 in South Carolina. All of these units are currently scheduled to start operation between late 2017 and 2019. (World Nuclear News, 4/11/2014)